You’re probably looking at little round spots that look like spiderwebs across the surface of your lawn wondering what they are what caused them.
These spots seem to pop up overnight and they’re typically seen in the morning and often in the summertime. They are more visible if the sun is shining across them. If you look a little closer, you might be able to see tiny little bubbles that can easily be dispersed.
What are these spiderweb-like spots on your lawn?
While these spots might look like small spiderwebs, what you’re actually seeing is mycelium. These spots are the start of a type of lawn fungus called dollar spot. This is a foliar disease which means that’s it’s in the leaf blade.
Dollar spot is characterized by “wicking” on the leaf blade.
Dollar spot is a fungus that live in the soil and it can sit in there for a long time waiting for the right conditions.
The good news is that’s its very rare for dollar spot to cause any long-term damage to your lawn. It’s pretty easy to control too!
The next stage of dollar spot
After these spiderweb-like spots on your lawn, you might notice some yellowing of the grass as the fungus moves into the next stage. You might be able to see a circular patch that resembles the shape of a dollar coin, hence the name dollar spot disease.
Over time these yellow spots can grow a lot bigger. In tall fescue, it’s common for these spots to grow to the size of a baseball. As they grow, they can end up grouping together leaving you with some strange looking irregular shapes.
One way to identify dollar spot disease is to look closely at the grass blades, right where the green meets the brown. If it is dollar spot, you should be able to see hour glass shaped lesions on them.
With dollar spot, the grass blades will always remain standing up. They won’t flatten.
What type of grass is affected by dollar spot?
While dollar spot can affect most warm and cool season grass types, some are more affected than others.
This is mostly a disease for finer bladed turf.
cool season grasses…
You’re most likely to find dollar spot in Kentucky bluegrass although it can also get into perennial ryes. It’s not found as often in turf type tall fescue.
warm season grasses…
Centipede and zoysia are most affected. I’ve also seen it shown up in bermudagrass too.
What causes dollar spot?
In order for any disease to develop, you need three things:
- A host plant (your grass)
- The pathogen/disease causing agent
- The right environment
The right conditions and the environment need to exist so that the pathogen can develop to affect the host plant.
Here are some of the ooor cultural practices and environmental factors like the weather that can facilitate the disease:
Lack of nitrogen
The biggest cause of dollar spot in the lawn is a lack of nitrogen in the soil.
Poor soil quality
If you have a well-established healthy soil with a good organic base that’s producing a lot of nitrogen, you’re very unlikely to get dollar spot to any significant degree.
Temperature and moisture changes
Temperature, moisture and humidity fluctuations can cause dollar spot. If you’ve had a lot of rain recently, you’re more likely to see dollar spot showing up in your lawn.
If you have a drought and there is a lack of moisture in the air to have a dew set in the evening then you’re not likely to see dollar spot disease. On the other hand, dew formed on the ground overnight and that’s stays on the grass until late into the morning can cause dollar spot.
It’s also common to see dollar spot if it’s been cool all spring and then it begins to get really warm in the summer.
Watering at night
If you’re watering at night, the water doesn’t get a chance to evaporate. The leaves can get too wet creating an environment for fungus in your lawn
I’d recommend watering in the morning instead.
Blunt mower blades
Blunt mower blades can increase the stress on your lawn making it more prone to disease so make sure that you keep mower blades sharp.
Some people say that you don’t need to treat dollar spot
I’ve heard a lot of people say that dollar spot will go away on its own. In some cases, it will go away if you just let it run its course but I’ve seen dollar spot last in a lawn for many years.
How to treat dollar spot
Treatment is pretty easy too so that’s what I’d always recommend.
Since this is a disease of the leaf, you can push it out with nitrogen. After a few plications, you should help it to grow out although it could take a few weeks to get rid of it if the disease has got well established in your lawn.
Use a fungicide
To treat the problem, I’d recommend using a system, liquid fungicide that is labeled for dollar spot. Even coverage is the key to good fungus control so I’d recommend going over your lawn twice if possible.
These applications tend to work better if you put them down prior to the disease so whenever you see some of the favorable conditions mentioned above, you might want to consider outing down a fungicide. As with any product, make sure you apply according to the label directions.
If you’re going to spray a fungicide, I’d look for a product with the active ingredient propiconazole.
It’s great to prevent fungus in its early stages.
If you’re going to use this fungicide, make sure you use at temperatures under 85F since it is a growth retardant. I’d recommend spraying in the evening time.
Tips for using a fungicide on dollar spot
- Whenever you spray a fungicide on your lawn, don’t let your pets or children go on the grass until the chemical has fully dried out.
- Make sure you’re wearing the proper PPE. It’s safer to wear it and it makes you look like a lawn pro too!
- You don’t need to worry about watering in the fungicide.
- Make sure you wash out your sprayer thoroughly. I’d recommend rinsing multiple times to get all of the chemical. You don’t want to be spraying two different chemical the next time you go to spray.
If you do have a problem with dollar spot disease…
Make sure that you are bagging your clippings every time your mow. That goes for any disease really. The last thing you want to do is spread the disease more around your yard.
You also want to stop doing things that contribute to the problem. Make sure you’re following a proper irrigation plan and make sure the lawn is getting the nutrients it needs.
Luckily dollar spot is not going to kill your lawn so you don’t need to be overly worried. It’s only going to affect the foliage on your grass and it can be treated fairly easily. You’re likely to find some disease in any lawn over the course of a year, that’s just the reality of being a lawn owner.
In most cases your lawn can withstand a certain amount of disease activity although some types of disease can be more of serious problem than others.
Dollar spot is not the only disease the can develop when given the right environment. Brown patch, powdery mildew and rust are other diseases that can develop in a lawn.
It’s almost important to recognize that diseases are not just created from temperature fluctuations and a varying climate. Things like mowing too short and inappropriately irrigating your lawn can also help set up the right conditions for diseases to develop.
As with most problems that can arise in a lawn, proper lawn care practice is your best form of the defense. The basics will go a long way to keeping out disease in your lawn so your grass can stay green throughput the growing season.